It is believed that lesions larger than those created by current electrophysiological therapy are needed to more consistently cure monomorphic ventricular tachycardia (MVT) of ischemic origins.
Conventional cardiac ablation systems designed to cure re-entrant supraventricular tachycardia (SVT), often create lesions in myocardial tissue with a penetration depth of about 3 to 5 mm and a lesion volume of less than 0.2 cm.sup.3, depending upon the size of the electrode and the amount of power that is applied.
However, to consistently cure MVT by ablation, a penetration depth greater than 3 to 5 mm and a lesion volume of at least 1 cm.sup.3 is estimated to be required.
The solution lies in larger electrodes. Yet, larger electrodes themselves pose problems of size and maneuverability that weigh against safe and easy introduction through a vein or artery into the heart.
A need exists for cardiac ablation catheters having that flexibility and maneuverability that permits safe and easy introduction into the heart and, once deployed inside the heart, emit energy sufficient to cause permanent, irreversible thermal damage to large regions of myocardial tissue.